Method of machining by electric current



Nov. 3, 1936. c. J. HOLSLAG METHOD OF MACHINING BY ELECTRIC CURRENT Filed Aug. 13, 1932 FIG. 4

INVENTOR CLAUDE J. HOLSLAG BY a; mg-w ATTORNEY Patented Nov. 3, 1936 PATENT GFFIQE IiIETHOD 0F MACHINING BY ELECTRIG CURRENT Claude J. Holslag, South Orange, N. 3., assignor to Electric Arc Cutting & Welding Company,

Newark, N. J.

Application August 13, 1932, Serial No. 628,780

1Clalm.

This invention relates to a method of machining metals by use of electric current.

In my Patents 1,321,309, issued November 11, 1919, and 1,451,392, issued April 10, 1923, I have shown electrodes and described the method of operation thereof for perforating and cutting metal.

In my present application, I show a new method of machining as distinguished from cutting, the object of which is to present a system of machining which is much faster than any other method of which I am aware and one in which the work or piece being machined is left in very nearly a finished condition, ready for use, that is, the part where the machining is performed, is left even and/or smooth.

My present improvement is especially advantageous in the manufacture of shafts or shafting as will be later pointed out.

The system of machining herein described will be readily understood by reference to the annexed drawing wherein:

Figure l is a side view of a form of apparatus equipped with two tools for machining purposes.

Figure 2 is a partial view of part of a lathe showing the application of my machining scheme to machining down a shaft.

Figure 3 is a plan view of another form of tool which may be used in the operation shown in Figures 1 and 2.

Figure 4 is an end view of Figure 3.

Figure 5 shows diagrammatically a further modification of my invention.

Figure 6 shows the application of the idea of my invention to a nibbling machine or high speed shaper and Figure 7 shows an application of the idea to a die-sinking tool.

In the various forms of apparatus used to illustrate my invention, Figure 1 shows a machine i such as may be used for polishing purposes in which a pulley 2 driven by a belt 3, runs between bearing supports 4 and 5. On the opposite threaded ends of the shaft 6 is fastened by any satisfactory means as by nuts I, rotary tools l1 and 18. These tools for machining purposes only, may be of any desirable composition and I have found that mild steel gives excellent results although I have used other metals in place of steel. I may in some cases even use carbon and/or carborundum rotary tools made with a suitable binder, it being understood that the composition of the rotary tools is such that it or they will be current conducting. The rotary tools H and I8 for machining purposes are mate- (ill- 219--=1) rially wider on their machining face thanv if the apparatus were going to be used for merely cutting of metals, in which case they would be in the form of relatively thin discs. The machining tools I! and i8 may be constructed, if desired as shown in Figure 3 wherein two metal discs l9 and 20, preferably of steel are mounted on the shaft 2i. Around the outer periphery of the discs l9 and 20 is fastened as by welding an annular ring 22 which serves as the machining surface between the tool and the work-piece, and if desired, the interior of the tool may be cooled by a fluid inlet passage 23 which may be supplied with one or more jet-tubes 26 to throw the cooling fluid directly against the inner part of the peripheral shoe 22. An outlet passage 25 acts to carry the cooling fluid away from the tool.

Another specific application of this type of tool is illustrated in Figure 2 wherein a lathe 26 carries on its feed-screw 21 a holder 28 carrying an electric motor 25, the motor being insulated from the holder 28 by the insulator 30. Current may be conveyed to the shaft 3i, that is to be machined down in any suitable manner as by brushccntact 32 connected to a suitable source of current. Likewise the tool 22 may be connected to the same source by brush-contact 33.

My invention is especially adapted for machining-down shafts where the same are relatively long for the reason that 1 have found there is little or no pressure existing between the rotating tool 32 and the shaft 3| so that the shaft will not be sprung in its lathe supports which is quite apt to be the case during the usual machine operatlons, especially where any attempt is made to hurry the operation by taking a deep cut with the usual cutting tool.

In any of the forms illustrated if any great amount of pressure is set up between the tool and the work-piece an arc will not be established and therefore its effect will not be obtained. Hence it naturally follows that the pressure between the tool and the work-piece is very low and even zero and in the case of machiningdown the shaft as illustrated in Figure 2, no detrimental pressure is applied between the tool and the shaft.

In Figure 5 I have illustrated diagrammatically a work-piece 39 to be operated upon by a tool in the shape of a wheel 40. The action of the tool may be augmented by the introduction of oxygen or other suitable gas through the nozzle M. In Figure 6 a specially designed tool 42 is adapted for use in a nibbling machine or highspeed shaper where the motion is up and down thisbeinc withtheadditionaladvantage that the shaitisnever sprung, ashasbeenernlained.

Inthetormsshowninl'igures5,6and7the electrical connections to the work and toolare not illustrated as their application will be obvious.butitismbekeptinmindthatthevoltace, current and reaetance in the current-supplyareadjustedtothe proper valuestoproduee thedesiredresultinaeeordancewiththeoperathe speed or rotation or movement of the tool is sufliciently high very rapid machining will result, due to the multitudinous number of rapidly shifting small arcs which are established and maintained between the moving tool and the wmkand themetalisrapidiymachined awayin a smooth even manner at a speed depending on the speed or rotation or movement 01 the tool and the value or the current flowing in the circult. In many cases I have found it desirable to adjust the source of current so that the voltage is about one-hail that required to hold a stationary are between the tool and the piece being operated upon. This reduction of voltage will take less power and will meet the demands for ordinary purposes, assuming of course that the tool is moved at the proper speed. Besides, with the lower voltage, a smoother operation can be made and wear on the tool will be much less and more even.

While I have shown the application at my machining method to a relatively stationary machine, a machining tool may be applied to a portable type oi apparatus.

Having thus described my invention, what I claim is:

The method of machining a work-piece of considerable length with respect to its diameter by a tool with very little or no pressure between the piece and tool during the machining operation thereby electing a poor contact, which consists in causing relatively rapid movement between the work-piece and tool in one plane at an angle to the axis oi! the work-piece, while at the same time causing relatively slow movement between the tool and work-piece in a direction parallel to the axis of the work-piece, applying a source oi current between the tool and work-piece, the voltage of the current being approximately onehalf that required to hold a steady are between the tool and work-piece to be machined while in such poor contact.

CLAUDE J. HOIfiLAG. 

